Chapter 6: Beyond Elasticity: Plasticity, Yielding And Ductility

Front 1

Yield strength

Back 1

Measures a materials strength. Materials with large yield strength are harder to deform. When metals deform they get stronger.

Front 2

Elastic

Back 2

Elasticity refers to the material's ability to deform in a non-permanent way, meaning that when the stress load is removed from the material it will recover its original form. A material will continue to deform elastically as the stress upon it increases until the elastic limit is reached.

Front 3

Plasticity

Back 3

plasticity describes the deformation of a (solid) material undergoing non-reversible changes of shape in response to applied forces. For example, a solid piece of metal being bent or pounded into a new shape displays plasticity as permanent changes occur within the material itself.

Front 4

Ductility

Back 4

Amount a material stretches before it breaks.

Front 5

Tensile strength

Back 5

The limit beyond which the material fails.

Front 6

Necking

Back 6

is a mode of tensile deformation where relatively large amounts of strain localize disproportionately in a small region of the material. The resulting prominent decrease in local cross-sectional area provides the basis for the name "neck

Front 7

True stress

Back 7

True stress is the applied load divided by the actual cross-sectional area (the changing area with respect to time) of the specimen at that load. Engineering strain is the amount that a material deforms per unit length in a tensile test. Also known as nominal strain.

Front 8

Toughness

Back 8

the ability of a material to absorb energy and plastically deform without fracturing

Front 9

Compressive strength - ceramics

Back 9

Ddfg

Front 10

Hardness

Back 10

Resistance of metal to plastic deformation, usually by indentation. However, the term may also refer to stiffness or temper, or to resistance to scratching, abrasion, or cutting.

Front 11

Yield Strain

Back 11

Ghuj

Front 12

Solution hardening

Back 12

Solid solution hardening is strengthening by deliberate additions of impurities or, more properly said by alloying. Alloying elements are generally bigger than those of the host material, making it harder for dislocations to move

Front 13

Vacancies

Back 13

A location in a crystal lattice where an atom is missing

Front 14

Substitutional solute atoms

Back 14

A point defect in which an impurity atom substitutes for a host atom

Front 15

Interstitial solute atoms

Back 15

A 0D point defects where a smaller atom fits in between other atoms in a crystal lattice

Front 16

Grain boundaries

Back 16

A planar defect that is the 2D interface between adjacent grains (single crystals) in a polycrystalline material

Front 17

Grains

Back 17

Ejde

Front 18

0D (point defects)

Back 18

Any defect that affects a few neighboring atoms or lattice points

Front 19

1D (line defects)

Back 19

The edge of a distorted plane of atoms in a lattice

Front 20

2D (planar) defects

Back 20

The interface between adjacent grains in a lattice

Front 21

Edge dislocation

Back 21

A 1D defect that is the edge of an extra half plane of atoms within a crystal lattice

Front 22

Screw dislocation

Back 22

1D line defect in which a path spirals around a dislocation line penetrating though otherwise individual parallel planes

Front 23

Interstices

Back 23

Ejeje

Front 24

Dislocation

Back 24

Front 25

Shear Force

Back 25

Jejs

Front 26

Slip planes

Back 26

Djeje

Front 27

Burgers vector

Back 27

The displacement vector that "close the loop" when traversing an equal number of lattice steps around the defect

Front 28

Dissolve

Back 28

D

Front 29

Solid solution hardening

Back 29

uses individual atoms distributed in the lattice to impede dislocation motion. Both substitutional and interstitial solute atoms perturb the atomic bonds in the lattice around them, “roughening” the slip plane, i.e. making it more difficult for the atomic bonding defect around a dislocation to move over the slip plane at this point.

Front 30

Interstitial solid solution

Back 30

J

Front 31

Impurities

Back 31

R

Front 32

Alloying

Back 32

S

Front 33

Hume-Rothery rules for solubility

Back 33

G

Front 34

Electronegativity

Back 34

G

Front 35

Valency

Back 35

Dg

Front 36

Dispersion strengthening

Back 36

A more effective way to impede dislocation is to disperse small, strong particles in their path. Disperse small solid particles of a high melting point compound into a liquid metal and to cast it to shape, trapping the particles in place.

Front 37

Precipitate strengthening

Back 37

If a solute is dissolved in a metal at high temperature when both are molten, and the alloy is solidified and cooled to room temperature, the solute precipitates as small particles.

Front 38

Work hardening

Back 38

uses plastic deformation to increase the dislocation density. Dislocations obstruct one another’s movement where they intersect, increasing the yield stress.

Front 39

Grain boundary hardening

Back 39

U

Front 40

Annealing

Back 40

Hro

Front 41

Hardening = strengthening

Back 41

Front 42

Solution hardening

Back 42

Rs

Front 43

Dispersion hardening

Back 43

Disperse small, strong particles into a liquid metal, trapping the particles when it is cast in to shape.

Front 44

Precipitate hardening

Back 44

Solute dissolved in a metal while both are molten; precipitates as small particles when cooled

Front 45

Work hardening

Back 45

Caused by the accumulation of dislocations generated by plastic deformation. Dislocation density is defined as the length of dislocation line per unit volume.

Front 46

Grain boundary hardening

Back 46

Front 47

Annealing

Back 47

Lj

Front 48

Dissolve (solution hardening)

Back 48

Dhd

Front 49

Substitutional sold solution (solution hardening)

Back 49

Dhd

Front 50

Interstitial solid solution (solution hardening)

Back 50

Hshs

Front 51

Impurities (solution hardening)

Back 51

Hsns

Front 52

Alloying (solution hardening)

Back 52

Hshs

Front 53

Zn+Cu= Brass (solution hardening)

Back 53

Brass uses strong solid-solution hardening, with the high levels of Zn added to the Cu. As the material is cast, no work hardening is used in this case (but brass is often “wrought”, i.e. shaped by deformation, and thus work hardened).

Front 54

Cu+Sn= Bronze (solution hardening)

Back 54

Hsjs

Front 55

Stainless steels (solution hardening)

Back 55

Dhd

Front 56

Hume-Rothery rules for solubility (solution hardening)

Back 56

Dhs

Front 57

Electronegativity (solution hardening)

Back 57

Ehe

Front 58

Valency (solution hardening)

Back 58

Ehe

Front 59

Al+SiC (dispersion hardening)

Back 59

Eje

Front 60

Al+Cu (precipitate hardening)

Back 60

Hsh

Front 61

Cu+Be (precipitate hardening)

Back 61

Ehe

Front 62

Rolling (Work hardening)

Back 62

Hee

Front 63

Bending (work hardening)

Back 63

Whe

Front 64

Shearing (work hardening)

Back 64

Jes

Front 65

Drawing (work hardening)

Back 65

Dhd